Abstract: Sustainable mining is generally considered to be an oxymoron because mineral deposits are viewed as nonrenewable resources that are fixed in the crust. However, minerals are conserved and recycled by plate tectonics which continually creates and destroys ore deposits. Though it is true that rock cycles have much longer periods than biomass cycles, the crust is essentially an infinite reservoir so long as we continue to invest in mineral exploration and processing technology. Implicit in the definition of sustainable development is the recognition that human development of resources in one reservoir may subsequently degrade resources supplied by another. The depreciation of overlapping and adjacent resources is often externalized in the cost to benefit accounting and cannot be sustained if the integrated cost/benefit ratio is greater than 1. The greatest obstacle to sustainability in mining is the expanding scale of excavation required to develop leaner ores because this activity degrades connected resources. In the case of open pit, sulfide ore mining the disturbed land may produce acid rock drainage (ARD). Because ARD will self-generate over the course of tens to hundreds of years the cost of controlling this pollution and rehabilitating mined lands is large and often spread over many generations. Secondary production of minerals from partially excavated deposits where there are preexisting environmental impacts and mine infrastructure help to reduce the risk of depreciating pristine resources, provided that new mining operations “do no (additional) harm” (Margoles, 1996). In turn, a percentage of the profits derived from secondary mineral production can be used for rehabilitation of the previously mined lands. These lands contain significant, albeit low grade, metal concentrations. These concepts are being developed and tested at the Mineral Park Sustainable Mining Research Facility where an in situ copper sulfide mining field experiment was conducted. Monitoring data and computer modeling indicate that ARD is not generated after closure. This is because the ore is not disturbed and is left saturated, whereas unsaturated conditions generate acidic drainage. The short term risk of groundwater contamination is mitigated by utilizing an exempt mine pit to capture any leach solutions that are not intercepted by the wellfield. Using green accounting techniques and transfer models it can be communicated that this mining scenario is an approach to sustainability.

Abstract: In einem alten französischen Bergwerk, in dem früher Blei und Silber abgebaut wurden, kam es nach dem Wiederanstieg des Grundwassers zu einer erhöhten Schwermetallbelastung von Quellgebieten, die einen Fluß mit Forellenbesatz schädigten. Zur Beseitigung dieser Grundwasserverunreinigung wurde das saure Grubenwasser mit erhöhten Eisen- und Zinkgehalten übertage gefaßt und einer Wasseraufbereitung unterzogen. In der für einen Durchsatz von 100 m(exp 3)/h konzipierten Wasseraufbereitung wurden die Schadstoffbestandteile durch Oxidation und anschließende Neutralisation mit Kalk (Anhebung des pH-Wertes auf 8,2 bis 8,3) gefällt, durch Zugabe eines Flockungsmittels gebunden und die Schlammbestandteile anschließend einem Eindicker und Filterpressen zugeführt. Der Kalkverbrauch wird mit 240 kg/d angegeben. Die tabellarisch zusammengestellten Analysenergebnisse zeigen, daß die Wasseraufbereitung einen sehr guten Wirkungsgrad hatte. Neben einer Anhebung des pH-Wertes von 6,5 auf 8,2 konnten die Schwermetallgehalte bei Fe von 22 mg/l auf 0,09 mg/l und bei Zn von 38 mg/l auf 0,4 mg/l abgesenkt werden.